a) 18\frac{8}{9} - 4 = 14\frac{8}{9}
Ответ: 14\frac{8}{9}
б) 17\frac{5}{14}-5\frac{3}{14} = (17-5) + (\frac{5}{14} - \frac{3}{14}) = 12 + \frac{2}{14} = 12\frac{1}{7}
Ответ: 12\frac{1}{7}
в) $$9\frac{5}{7} - 3\frac{6}{7} = 8\frac{12}{7} - 3\frac{6}{7} = (8-3) + (\frac{12}{7} - \frac{6}{7}) = 5 + \frac{6}{7} = 5\frac{6}{7}$$
Ответ: 5\frac{6}{7}